ISRO To Launch Indian Data Relay Satellite System As Communication Hub In Sky As Part of Manned Mission

ISRO To Launch Indian Data Relay Satellite System As Communication Hub In Sky As Part of Manned Mission

The two-satellite IDRSS will maintain a continuous communication link with India's remote sensing/earth observation satellites and also with the Geosynchronous Satellite Launch Vehicle Mark III (GSLV Mk III) that would carry three Indian astronauts to space in 2022.

As part of its proposed manned space mission, India will launch the Indian Data Relay Satellite System (IDRSS) to improve data relay and communication links with its remote sensing/earth observation satellites, said a top official of the ISRO.

The two-satellite IDRSS will maintain a continuous communication link with India's remote sensing/earth observation satellites and also with the Geosynchronous Satellite Launch Vehicle Mark III (GSLV Mk III) that would carry three Indian astronauts to space in 2022.

"We are planning to launch two satellites under IDRSS. The first one is expected to be launched in 2019," K. Sivan, Chairman, Indian Space Research Organisation (ISRO), told IANS.

Officials told IANS that continuous communication link was important in the case of human space mission as the rocket carrying the Indian astronauts cannot be without a link.

Manned mission apart, IDRSS will maintain a continuous communication link with Indian remote sensing/earth observation and other satellites in low earth orbit.

IDN Editor's Desk: What is a Relay Satellite?

Like in a relay race, where runners pass the baton to the next runner to run the next leg of the race, the Tracking and Data Relay Satellite (TDRS) works similarly with satellite's information to transfer data between the ground and space.

Satellites in orbit cannot pass along their information to the ground stations on Earth if the satellite does not have a clear view of the ground station. Therefore, TDRS serves as a way to pass along the satellite's information. 10 TDRS sit about 35,400 kilometres (22,000 miles) above the Earth and are able to forward information from a satellite until it reaches the appropriate ground station in view. TDRS can also send information from the ground to the satellite to tell the satellite what to do (take a picture, turn a sensor or off, send stored data back or change its orbit). TDRS will allow ISRO to have extensive sub-continental coverage of all the satellites-24 hours a day- without having to build extra ground stations on Earth.

The two IDRSS satellites will be placed in geostationary orbit, enabling the satellite to satellite communication and transfer data. The IDRSS satellites can see about 80 percent of the area where Indian remote sensing satellites are orbiting.

The proposed system will also reduce the dependence on the ground stations in tracking satellites, an ISRO official told IANS.

India has the largest remote sensing satellite system orbiting in the space.

Further, the data capture and transfer capabilities of remote sensing satellites are increasing with newer technologies.

"India is launching many satellites -- nano, micro and small -- in the low earth orbit. Their monitoring is now done by the ground stations in India and outside. But monitoring of satellites by ground station has gaps. The visibility of Indian remote sensing satellites for ground stations is not more than 10-15 minutes and in some cases, it is five minutes or less," an industry expert told IANS preferring anonymity.

There is also a heavy reliance on ground stations in other countries, he added.

He said with IDRSS in place, the visibility range will go up for monitoring and communicating with earth observation satellites.

The other benefit is that the communication and data transfer could be in real time as the remote sensing satellites can relay the data gathered to IDRSS satellites which in turn can transmit them to the ground.

The expert said IDRSS will be like a hub as it can receive the commands from the ground stations and in turn relay the same to other satellites.

The IDRSS can also monitor a rocket from the time it lifts off from the launch pad.

Space-faring nations like the US, China, Japan and Europe have such data relay satellite systems.

The IDRSS will also be of great use for India's strategic sectors as the data can be obtained on real-time basis, another expert told IANS, preferring anonymity.